Slotted cylindrical electrode electrostatic separator



June 21, 1966 J. H. CARPENTER 3,256,985

SLOTTED CYLINDRIGAL ELECTRODE ELECTROSTATIC SEPARATOR Filed Deo. 4, 19615 Sheets-Sheet l my@ J.

ATTORNEYS June 2l, 1966 J. H. CARPENTER SLOTTED CYLINDRICAL ELECTRODEELECTROSTATIC SEPARATOR 3 Sheets-Sheet 2 Filed Dec. 4, 1961 INVENTORSLOTTED CYLINDRICAL ELECTRODE ELECTROSTA'I'IC SEPARA'I'OR Filed Dec. 4,1961 3 Sheets-Sheet 5 INVENTOR BwmMw/w ATTORNEYS United States Patent O3,256,985 SLOTTED CYLINDRICAL ELECTRODE ELECTROSTATIC SEPRATOR JamesHall Carpenter, 4120 Haines St., Jacksonville, Fla.

Filed Dec. 4, 1961, Ser. N0. 157,321 8 Claims. V(Cl. 209-129) Thisinvention relates to the separation of particles and more particularlyto the separation of fibers or other elongated particles fromsubstantially non-elongated particles.

Separation of minerals and other materials has been accomplished byvarious vtechniques in accordance with certain characteristics of thematerials being separated such as electrical conductivity, magneticattraction, size and the like. It is frequently desirable to separateminerals and other materials in accordance with the shape of theparticles but there has been a lack of a commercially successfulapparatus for effectively accomplishing such separation.

It is a primary object of this invention to provide an improvedseparator which effectively removes libers or other elongated particlesfrom substantially non-elongated particles. f

Another object of this invention is to provide an improved high tensionapparatus for separating dipolar particles from substantially equipolarparticles..

Another object of the invention is to provide an irnproved high tensionseparator wherein the separated particles are efeiently and easilycollected.

Still another object of the invention is to provide an improved hightension separator apparatus which is substantially free of moving partsand is economical to construct and maintain. v

Generally and in accordance -with one aspect of the invention there isprovided an apparatus for separating elongated particles fromsubstantially non-elongated par ticles comprising an upright atelectrode, an upright generally cylindrical hollow electrode spaced fromsaid flat electrode to permit an unseparat-ed mixture of elongated andsubstantially non-elongated .particles to fall freely by lgravity in thespace therebetween, said hollow electrode having a longitudinal slotextending through its side Wall narrower than and facing said flatelectrode, and means to electrically charge said electrodes withopposite polarity to create an electrostatic field therebetweento causethe elongated particles to move toward said slot away from thenon-elongated particles. The bottom of the slotted electrode ispreferably inclined away from the flat Wall of the opposing electrode.The conguration of the electrodes is such as to provide converging linesof electrostatic force extending between them so that the elongatedparticles which become dipolar move horizontally in the direction ofconvergence and the substantially nonelongated particles which aresubstantially equipolar drop vertically downwardly. p

Although the invention is useful in separating many different types ofelongated or dipolar particles from substantially non-elongated orequipolar particles, it is particularly advantageous in the separationof elongated asbestos fibers from substantially non-elongated particlesor lumps of asbestos rock or foreign materials. Thus, the invention willbe described primarily with reference to the separation of asbestos.

The invention having been generally described, a preferred specificembodiment will now be set forth in detail with reference to theaccompanying drawings in which.:

FIGURE 1 is a front elevation partially broken away of a separatingapparatus according to the invention;

FIGURE 2 is a side elevation partially broken away of such apparatus;

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FIGURE 3 is a fragmentary vertical section taken along the line 3-3 ofFIGURE 2; and

FIGURE 4 is a horizontal section taken along the line 4 4 of FIGURE 3.

Depicted in the drawing is a three stage apparatus according to theinvention which apparatus includes a housing 11 constructed in threesections 12, 13 and 14 which are stacked upon each other in verticalalignment. Each of the housing sections includes front and rear wallsand a pair of channel-shaped side covers 15, 16. The housing sections12, 13 and 14 enclose separating assemblies 17, 18 and 19,-respectively. Since such assemblies are identical to each other only oneof them will hereinafter be described in detail.

Each of the separating assemblies receives in turn an unseparatedmixture of asbestos particles including thin elongated fibers 21 andsubstantially non-elongated lumps 22. As will be described in moredetail hereinafter, the unseparatedr mixture of particles is fed firstthrough a hopper 23 to the separating assembly 17 where elongated fibers21 are removed from the mixture and deposited on one side of a splitterplate 24 where they slide down an inclined bottom wall 25 which beginsin the housing section 12 and extends into the top of housing section 13into the interior of the channel-shaped housing cover 15. Since all ofthe channels 15 of the three sections are in communication with eachother, the particles drop straight downwardly to the bottom of thehousing 11 where they are collected by any suitable means. The portionof the mixture containing the lumps or non-elongated particles falls tothe other side of the splitter plate 24 `and slides down the inclinedbottom wall 26 into the hopper 23 of the separator assembly 18. Theseparating process is then repeated and additional elongated 'fibers 21are removed from such mixture and deposited into the channel 15. Theremaining portion of the mixture is ypassed downwardly into the hopper23 of the separator assembly 19 where a final separation is effected. Itwill be understood that only one separator vassembly or as many suchassemblies Ias desired may be employed. Moreover, the elongated fibers21 which are separated in any particular separating assembly may besubjected to further separation in another such assembly to remove Ianysubstantially non-elongated particles which may still remain among g thefibers.

With particular reference to the separator assembly 18, one of suchassemblies will now be described in detail. The unseparated mixture ofyasbestos particles is deposited from the hopper 23 of the separatorassembly 18 onto'a feeder 20 which may be any suitable device for movingthe particles to the desired location before permitting them to dropdownwardly by gravity. The ow of the particles from the hopper 23 intothe trough 25 may be controlled by an `adjustable ap 31 at the hopperthroat. The'specic feeder shown in the drawing comprises a commerciallyavailable vibratory feeder which includes a vibrating trough 25 and amotor 26 which reciprocates the trough in the conventional manner topropel the particles longitudinally therealong. The motor 26 is attachedto a bracket 27 which in turn is mounted on a table 28 which is weldedor otherwiseaixed to the housing section 13. It will be understood thanan endless belt or other type of conveyor may be employed instead of thevibratoryv feeder.

The unseparated mixture of particles falls from the end of the vibratorytrough y25 between 'a pair of spaced upright electrode assemblies 32 and33. The electrode assembly 32 comprises a wide iiiat plate 34 havingrounded 0 top and bottom edges 35 and 36. The plate 34 is stif- Y 42 ofthe `table 28. Suitable nuts 43 are provided to adjust the position ofeach rod 41 thereby moving the bottom of the plate 34 horizontallytoward or away from the electrode 33. The electrode plate 34 isconnected to ground .by the wire 44.

The electrode assembly l33 includes a plurality of electrode components45 each of which is substantially in the form of a hollow cylinder. Eachcylindrical electrode 45 is open ended and provided `with a longitudinalslot 46 extending through the cylinder wall facing the plate electrode32. The slot 46 is narrower than the plate 34 and preferably extends theentire length of the cylindrical electrode 45. The slot 46 is delined bythe enlarged and rounded edges 47 and 48 running longitudinally of thelaxis of each cylindrical electrode 45. .Such rounded edges 47 and 4Sand the rounded edges 35 and 36 of the plate 34 prevent or minimizeundesirable corona discharge which would Itend to occur from any sharpedges on Ithe electrodes. The electrode components 45 are welded orotherwise attached to a pair of generally horizontal supporting bars 5lwhich are mounted at vertically spaced positions at the rear of suchelectrodes. Each of the bars 51 is attached -to a channel-shaped bracket52 which in turn is supported by the lower end of one of the insulatorassemblies 53 and 54. The insulator assemblies 53 and 54 are connectedat their upper ends to brackets 5S and 156, respectively. The lower endof the electrode assembly 33 is inclined rearwardly away from theelectrode 32 for a purpose to tbe explained hereinafter. The electrodeassembly l33 is connected to a source of high voltage electricity by thewire v57.

In addition to or instead of the rearward inclination, the cylindricalelectrode components may if desired be slightly inclined laterally withrespect to -a vertical plane passing between the spaced electrodes.

The plate electrode 32 and the cylindrical electrode 33 are electricallyconnected to a high voltage power supply to permit such electrodes to becharged with opposite polarity to create an electrostatic `field betweenthe electrodes. The electrostatic ield between the oppositely chargedelectrodes has lines of force which converge from the `fiat plateelectrode 32 toward each of the longitudinal slots 46 in the cylindricalelectrode 33. Charging of the electrodes may be accomplished, forexample, by connecting the electrode 33 to a high voltage power sourceto receive a negative charge while the elec-trode 32 is grounded toreceive a positive charge. Although the polarity may be reversed, `bestresults are usually obtained with `the cylindrical electrode negativeand the plate electrode positive. It is believed that a higher degree ofundesirable corona discharge occurs when the plate electrode isnegatively charged.

When the asbestos bers 21 and lumps 22 are dropped from the vilbratoryfeeder trough 25 substantially all of such particles initially fallfreely out of contact with either electrode. When the particles aresubjected to the converging electrostatic lines of force between theelectrodes, the elongated iibers pass through ythe slots 46 into theinterior of the cylindrical electrode components 45. It is -believedthat the electrostatic field causes the elongated particles to `becomedipoles which align themselves 4in the direction of the lines of force.Such dipoles then tend to move in the direction of convergence of thelines of force. High speed motion pictures reveal that the accelerationof the particles in the direction of the convergence of the lines offorce increases with the ratio between the length of the particles totheir thickness. The substantially non-elongated lumps or chunks remainsub- 1, stantially equipolar and thus do not tend to move along thelines of force.

The spaced electrodes 32 and 33 may be characterized by any specificconfiguration which provides converging lines of force between Itheelectrodes when they are charged by a high volt-age source. Thus, anydipolar particles will tend to be separated from any substantiallyequipolar particles. Moreover, in view of the circumstance that theacceleration of the particles in the direction of the convergence of thelines of force increases with the length of the particles to theirthickness, the apparatus of the invention may be employed to separateparticles having a greater ratio of length to thickness from particleshaving a lesser ratio of length kto thickness. The term substantiallynon-elongated as employed herein denotes particles of such a lesserdegree of elongation as to `be essentially unaffected by `the electrodesof the apparatus described and thus fall substantially vertically.

The most desirable horizontal spacing between the electrodes 32 and 33depends upon several -factors including the character of the particlesbeing separated, the voltage applied and the like. Where the lsp-acingis too close, the fibers tend to link together in chains extending fromthe edges of the slots 46 to the plate 34. Where the spacing is toogreat, good separation is not achieved. The determination of the optimumspacing for any set of circumstances is within the skill of the art.

As best shown in FIGURE 3, the lower portion of the electrode 33 ispreferably inclined rearwardly away from the electrode 32. Suchinclining of the electrode 33 has a decided advantage. With sucharrangement, the upper ends of the electrodes 32 and 33 may berelatively close together to afford maximum separating effect withoutinducing chaining of the fibers across the gap between the electrodes.lf the bottom of electrode 33 is that close to the electrode 32,however, there is a relatively small space in which to divide theelongated iibers from the nonelongated chunks. It has been found thatthe bottom of the electrode 33 may be inclined rearwardly away from theelectrode 32 without materially deltracting from the etectiveness of theseparation. The fibers at the top of the separating zone are acceleratedin the direction of the electrode 33 and are also accelerated downwardlyby gravity and lthus they move in a trajectory. The electrode 33 may beinclined generally to correspond to such trajectory and thereby affordmaximum separating effect at the top and provide a relatively wide spacefor division of the particles at the bottom.

Moreover, the rearward inclining of the lower portion of the electrode33 decreases the possibility of actual contact between the fibers 21with the surface of the electrode 33. Such contact is undesirablebecause it imparts a negative charge to the particles and tends to movethem back toward the positively charged plate electrode. Theelectrostatic lines of force within each component of the cylindricalelectrode 33 converge to the cylinder axis and thus the iibers `tend toremain at such axis. The momentum of the particles entering thecylinder, however, tends to cause them to move toward the .rear of thecylinder. The effects of such momentum are minimized by inclining thebottom of the cylindrical electrode away from the separating zone. Ithas `been found that a tilt of about 15 from the vertical is highlysatisfactory in most installations.

At the bottom of the separating zone between the electrodes, theelongated fibers 2l fall to one side of the splitter plate 24 and thenon-elongated chunks or rocks fall to the opposite side of such splitterplate. The position of the upper end of the plate 24 preferably may beadjusted to Various positions across the separating zone. Suchadjustment may be achieved by mounting the splitter plate 24 on a pivot58. After passing the splitter plate the elongated fibers slidedownwardly along the inclined floor 25 and move through an opening 59 inthe housing wall into the interior of the channel cover 15. The rocksVparts are in the vibratory feeder.

or chunks move downwardly along the inclined floor 26 into the hopper 23of the next lower separator assembly. The apparatus of the invention issimple in construction and embodies few moving parts. Indeed, the onlymoving The components for achieving the actual separation of theparticles involve no moving parts. Further, the gravity feed systemeliminates the necessity for conveyors for moving the particlesthrough'the apparatus. Accordingly, the device is very economical toconstruct, operate and maintain.

'There has been illustrated and described what is considered to be apreferred embodiment of the invention. It will be lunderstood, however,that various modifications will occur to persons skilled in the artwithout departing from the scope of the invention which is definedsolely' by the appended claims.

I claim:

1. An apparatus for separating elongated particles from substantiallynon-elongated particles comprising an upright flat electrode, an uprightgenerally cylindrical hollow electrode spaced from said flat electrodeto permit an unseparated mixture of elongated and substantiallynon-elongated particles to fall freely by gravity in the spacetherebetween, said hollow electrode having a longitudinal slot extendingthrough its side wall narrower than and facing said flat electrode, andmeans to electrically charge said electrodes with opposite polarity tocreate an electrostatic field therebetween to cause the elongatedparticles to move toward said slot away from the non-elongatedparticles.

2. The apparatus as recited in claim 1 wherein said charging meansimparts a negative charge to said cylindrical electrode.

3. The apparatus as recited in claim 1 wherein the lower end of saidcylindrical electrode is rearwardly inclined with respect to said flatelectrode.

4. The apparatus as recited in claim 1 wherein said slot Vand said atwall are characterized by rounded edges.

5.- The apparatus as recited in claim 1 wherein said slot extends theentire length of said cylindrical electrode.

6. The apparatus as recited in claim 5 wherein said cylindricalelectrode is open at both ends.

7. An apparatus for separating elongated particles from substantiallynon-elongated particles comprising an vupright plate electrode, anupright generally cylindrical hollow electrode spacedfrom said plateelectrode and having a longitudinal slot extending through itsside wallnarrower than and lfacing said plate electrode, means to deposit anunseparated mixture of elongated and substantially non-elongatedparticles into the -upper portion of the space between said electrodesto permit said particles to drop freely downwardly by gravity in saidspace, means to electrically charge said electrodes with oppositepolarity to causethe elongated particles to move toward said slot awayfrom the non-elongated particles, and means for collecting the elongatedparticles separately from the non-elongated particles.

8. The apparatus as recited in claim 7 wherein said charging meansimparts a negative charge to said cylindrical electrode.

References Cited by the Examiner UNITED STATES PATENTS 1,995,790 3/1935Anderson 55-154 X 2,706,044 4/ 1955 Cook 209-127 2,782,923 2/ 1957 Cook209-127 v2,803,344- 8/ 1957 Morrison 209-127 2,839,189 6/ 1958 Johnson209-127 FOREIGN PATENTS 644,638 5 1937 Germany.

FRANK W. LUTTER, Primary Examiner.

HARRY B. THORNTON, ROBERT A. OLEARY,

Examiners.

1. AN APPARATUS FOR SEPARATING ELONGATED PARTICLES FROM SUBSTANTIALLYNON-ELONGATED PARTICLES COMPRISING AN UPRIGHT FLAT ELECTRODE, AN UPRIGHTGENERALLY CYLINDRICAL HOLLOW ELECTRODE SPACED FROM SAID FLAT ELECTRODETO PERMIT AN UNSEPARATED MIXTURE OF ELONGATED AND SUBSTANTIALLYNON-ELONGATED PARTICLES TO FALL FREELY BY GRAVITY IN THE SPACETHEREBETWEEN, SAID HOLLOW ELECTRODE HAVING A LONGITUDINAL SLOT EXTENDINGTHROUGH ITS SIDE WALL NARROWER THAN AND FACING FLAT ELECTRODE, AND MEANSTO ELECTRI-